1. Technical Field of the Invention
The present invention relates to a 4-stroke reciprocating piston engine having a supercharging piston.
2. Description of the Prior Arts
(Patent Literature 1) and (Patent Literature 2) invented by the present applicant, for which a patent right has been respectively granted discloses a “Bidirectional type reciprocating piston engine composed of eight cylinders having a crankshaft including four crank pins and having a pair of bidirectional reciprocating pistons mounted on the respective crank pins.”
[Patent Literature 1]
                Japanese Patent Publication No. 3137283[Patent Literature 2]        United States Patent Publication No. 5873339        
However, although complete dynamic balance is ensured in the case of eight-cylinder construction described in (Patent Literature 1) and (Patent Literature 2), two pistons are mounted in a single crank pin in a bidirectional reciprocating piston engine, and in a case of four-cylinder construction, the number of crank pins becomes two, wherein there remains a problem in that it is impossible to secure dynamic balance as it is.
In a prior art piston engine, the four-cylinder configuration is most frequently used as a piston configuration. It is possible to widen the scope of application of a bidirectional reciprocating piston engine if a mechanism in which a construction having a fewer cylinders than the eight-cylinder construction is enabled in the bidirectional reciprocating piston engine.